City gas meters in the medium pressure range for custody transfer have been dominated by mechanical technology such as turbine or rotary meters. These meters have been on market for over 160 years enjoying excellent service, life and reliability. However, the turbine meter is greatly suffered from a small dynamic range while the rotary meter is quite vulnerable to the damage caused by floating particles in the flow medium. For the rotary meter, event it is only partially clogged or damaged by the floating particles; the meter would still be affected in terms of repeatability and accuracy of flow measurement. Once the rotary meters got completely clogged, the rotary meter will stop rotating and fail the functionality. In addition, these mechanical meters requires heavy maintenances services and an add-on flow computer to compensate the environment variation of pressure and temperature conditions which could naturally induce the volumetric changes of gas medium. The drawbacks of the flow computer is not only it is extremely pricey (more expensive than the meter itself in many cases) but also it adds additional metrology errors to the flow measurement. Since the early 1980s, many efforts have been made for a non-mechanical gas meter that shall have the capability to self-compensate the variation caused by temperature and pressure and the capability for remote data communication in a secure method. The commercially available non-mechanical gas meters comparative to mechanical meters are still rarely perceived, particularly for the medium pressure range city gas industrial and low pressure range commercial users.
Therefore, it is very desirable to have such new type of non-mechanical technology and take over the custody transfer for gas meters in medium pressure range, which is disclosed in current invention.